/*
 * Created on Oct 29, 2008
 * Created by Paul Gardner
 * 
 * Copyright (C) Azureus Software, Inc, All Rights Reserved.
 * 
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; version 2 of the License only.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.
 */

package com.aelitis.azureus.core.util.bloom.impl;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.gudy.azureus2.core3.util.SystemTime;

import com.aelitis.azureus.core.util.bloom.BloomFilter;

public class BloomFilterRotator implements BloomFilter {
    private volatile BloomFilter current_filter;
    private int current_filter_index;

    private final BloomFilter[] filters;

    private long start_time = SystemTime.getMonotonousTime();

    public BloomFilterRotator(BloomFilter _target, int _num) {
        filters = new BloomFilter[_num];

        filters[0] = _target;

        for (int i = 1; i < filters.length; i++) {

            filters[i] = _target.getReplica();
        }

        current_filter = _target;
        current_filter_index = 0;
    }

    public BloomFilterRotator(Map<String, Object> x) {
        List<Map<String, Object>> list = (List<Map<String, Object>>) x.get("list");

        filters = new BloomFilter[list.size()];

        for (int i = 0; i < filters.length; i++) {

            filters[i] = BloomFilterImpl.deserialiseFromMap(list.get(i));
        }

        current_filter_index = ((Long) x.get("index")).intValue();

        current_filter = filters[current_filter_index];
    }

    public Map<String, Object> serialiseToMap() {
        Map<String, Object> m = new HashMap<String, Object>();

        serialiseToMap(m);

        return (m);
    }

    protected void serialiseToMap(Map<String, Object> x) {
        synchronized (filters) {

            String cla = this.getClass().getName();

            if (cla.startsWith(BloomFilterImpl.MY_PACKAGE)) {

                cla = cla.substring(BloomFilterImpl.MY_PACKAGE.length());
            }

            x.put("_impl", cla);

            List<Map<String, Object>> list = new ArrayList<Map<String, Object>>();

            for (BloomFilter filter : filters) {

                list.add(filter.serialiseToMap());
            }

            x.put("list", list);
            x.put("index", new Long(current_filter_index));
        }
    }

    public int add(byte[] value) {
        synchronized (filters) {

            int filter_size = current_filter.getSize();
            int filter_entries = current_filter.getEntryCount();

            int limit = filter_size / 8; // capacity limit

            if (filter_entries > limit) {

                filter_entries = limit;
            }

            int update_chunk = limit / filters.length;

            int num_to_update = (filter_entries / update_chunk) + 1;

            if (num_to_update > filters.length) {

                num_to_update = filters.length;
            }

            // System.out.println( "rot_bloom: cur=" + current_filter_index + ", upd=" + num_to_update + ",ent=" + filter_entries );

            int res = 0;

            for (int i = current_filter_index; i < current_filter_index + num_to_update; i++) {

                int r = filters[i % filters.length].add(value);

                if (i == current_filter_index) {

                    res = r;
                }
            }

            if (current_filter.getEntryCount() > limit) {

                filters[current_filter_index] = current_filter.getReplica();

                current_filter_index = (current_filter_index + 1) % filters.length;

                current_filter = filters[current_filter_index];
            }

            return (res);
        }
    }

    public int remove(byte[] value) {
        int res = 0;

        for (int i = 0; i < filters.length; i++) {

            BloomFilter filter = filters[i];

            int r = filter.remove(value);

            if (filter == current_filter) {

                res = r;
            }
        }

        return (res);
    }

    public boolean contains(byte[] value) {
        return (current_filter.contains(value));
    }

    public int count(byte[] value) {
        return (current_filter.count(value));
    }

    public int getEntryCount() {
        return (current_filter.getEntryCount());
    }

    public int getSize() {
        return (current_filter.getSize());
    }

    public BloomFilter getReplica() {
        return (new BloomFilterRotator(current_filter, filters.length));
    }

    public long getStartTimeMono() {
        return (start_time);
    }

    public void clear() {
        start_time = SystemTime.getMonotonousTime();

        for (BloomFilter filter : filters) {

            filter.clear();
        }
    }

    public String getString() {
        return ("ind=" + current_filter_index + ",filt=" + current_filter.getString());
    }
}
